Somerton and Donaldson. Parasitism of Lithodes aequispinus by two species of Careproctus 
879 
Tabie 3 
Incidence of snailfish (Careproctus spp. ) egg clusters within golden king crab (Lithodes aequispinus). Included are the total 
landed catch in numbers of live and dead crab, number of crab in each category examined, and the number with egg masses. 
Sampling type 
Area 
Condition 
Catch 
Crabs 
examined 
Crabs with 
fish eggs 
Percent 
infested 
Incidence in male crabs >135 mm CL 
1996 port 
Bering Sea 
live 
12788 
302 
25 
8.3 
dead 
351 
44 
7 
15.9 
Aleutian Is. 
live 
46206 
603 
15 
2.5 
dead 
1508 
343 
14 
4.1 
1982 survey 
Bering Sea 
live 
55 
24 
43.6 
Incidence in female crabs and male crabs <135 mm CL 
1996 at-sea 
Aleutian Is. 
male 
1641 
12 
0.7 
female 
1631 
4 
0.2 
1982 survey 
Bering Sea 
male 
183 
44 
24.0 
female 
274 
26 
9.5 
40 60 80 100 120 140 160 
Carapace length (mm) 
Figure 9 
Incidence of Careproctus eggs and larvae, predicted by the general- 
ized linear model, for male (solid line) and female (dotted line) golden 
king crab as a function of carapace length. 
DNA amplification. Careproctus furcellus, C. 
rastrinus, and C. cypselurus fish samples could 
be readily distinguished in the RFLP analysis. 
Of the 10 usable egg and larvae samples, two 
were identified as C. furcellus and eight clearly 
differed from all of the fish samples. 
Effect of the egg masses on gill function 
The presence of egg masses within the bran- 
chial chamber of a crab was associated with 
three distinct pathological conditions of the 
gills. First, egg masses compressed the gills 
so strongly that a distinct impression of the 
egg mass was left on the gill surface (Fig. 10, 
upper, p. 880). Second, gills on the infested 
side of a golden king crab were often darker in 
color than those on the opposing side (Fig 10, 
lower, p. 880). Third, gills on the infested side 
often had areas of blackened, necrotic tissue 
(Fig. 10, p. 881). Several gills with necrotic 
tissue were examined microscopically after 
standard histological preparation. 3 A stage- 
wise progression of tissue damage was evi- 
dent, beginning as small lesions with hemo- 
cyte encapsulations. As the lesions increased 
in size, they were more likely to be melanized, 
indicating a chronic condition, and often oc- 
cluded one or more gill lamellae. Small (occlud- 
ing one or more lamellae) to medium size (occluding 
the gill stem) lesions typically possessed new cuticle 
3 Morado, F. 1996. Alaska Fisheries Science Center, 7600 Sand 
Point Way NE, Seattle, WA. Personal commun. 
and normal respiratory epithelium underneath the af- 
fected area, indicating that the gill tissue would be re- 
generated during the next molt. In extreme cases, all 
of the gills on the affected side of the body were re- 
duced to blackened stubs (Fig. 10, p. 881). 
